Joyce, U.S. Pat. No. 2,462,402 (Feb. 22, 1949) discloses a process for the production of highly halogenated fluoroalkanes which comprises contacting TFE with a polyhalogenated alkane,preferably a methane, containing at least one chlorine atom and no more than two fluorine atoms, in the presence of a polyvalent metal halide catalyst, preferably aluminum chloride.
U.S. Pat. No. 2,462,402, to Coffman, et. al., is referenced in the Journal of the American Chemical Society, Vol. 71, pages 979-980 (1949) which discloses that reacting CHClF2 (chlorodifluoromethane) while in the presence of aluminum chloride with TFE produces CHC12F5 having one less F atom than the sum of fluorine atoms in the reactants. Likewise, CHClF2 reacting with CTFE yields CHC13F4.
Paleta, in a review article "Fluorine Chemistry Reviews", Vol. 8, page 51 (1977) states: "The ionic addition reactions of fluoromethanes in the presence of aluminum chloride are limited to the monofluoro derivatives only. When in contact with aluminum chloride, both difluorodichloromethane and difluorochloromethane were found to undergo a rapid disproportionation with the formation of monofluorochloromethanes (along with some further compounds) that are able to add to fluoroethylenes.".
The disclosure of each of the previously identified references is hereby incorporated by reference.